The present invention relates to an apparatus for producing punched apertures in a wall of a component.
Punching a hole in an exterior wall of a tubular member is practiced in many areas of industry. The location and size of the holes facilitate access either through or into the interior of the tubular member, at positions other than the ends of the tube. The punching of holes through sheet metal portions also facilitate access from one side of the sheet to the other. Commercially available punching units are used to manufacture these holes, due to their repeatability of position and orientation of the holes. Drills are another device that can be used to create these holes, but the drills can create complications due to a formation of burrs at an edge of the hole, a formation of chips, and a potential need for a lubricant. In addition, the drills are typically slower for hole formation than the punching units, which also have an added benefit of being able to produce hole shapes other than circular.
One example of a punching unit is taught by U.S. Pat. No. 3,848,497. This patent teaches a mandrel attached to a frame, by means of a fastener in the interior of the unit. A tube to be punched is slid over the mandrel, above which lies a punch. The punch includes a female die member and the mandrel includes a male die member. One disadvantage of this unit is that setup time for the female and male die members can be lengthy, due to the number of fasteners and adjustments used to assemble the unit. Accordingly, the punching unit of the ""497 patent is not readily adaptable to produce a variety of different sized or shaped holes, without incurring substantial down-time to change the members that correspond to a desired hole geometry. Therefore, it is common for a manufacturer to have a series of punching units, one for each hole geometry to be produced. This arrangement can reduce down-time, but requires the manufacturer to purchase multiple punching units.
Another punching unit is taught by U.S. Pat. No. 4,744,276, which discloses a punch assembly for producing a series of holes along a length of the tubular member. The tubular member is fed progressively over the mandrel, so that a punch head can be operated cyclically in order to punch a series of holes in the tube. Unfortunately, the punching unit of the ""276 patent also suffers from the same adaptability problem as the ""497 patent. Furthermore, the mandrel of the ""276 patent is replaced as a single unit when it is worn out, which is undesirable. Mandrels are typically precision made to close tolerances and can be expensive to replace.
It is in object of the present invention to obviate or mitigate some of the above presented disadvantages by providing an adaptable punching unit.
According to the present invention there is provided an apparatus for punching an aperture of selected geometry in a wall of a component. The apparatus comprises a frame for supporting the component and a tool and die assembly releaseably securable to the frame. The tool and die assembly has a punch operatively coupled to a mandrel and comprises a male die member and female die member cooperating to form the aperture in the wall. One of the members is coupled to the mandrel and the other of the members is coupled to the punch. The mandrel is releasably securable to a portion of the frame and the punch is releasably securable to another portion of the frame. The longitudinal axis of the mandrel is placed in a fixed position relative to the longitudinal axis of the punch once each of the mandrel and the punch is secured to the frame. The male and female portions of the tool and die assembly arc interchangeable as a sot and aligned in a fixed position to one another once said mandrel and said punch are secured. The male and female portions cooperate to provide a selected one of a plurality of predetermined aperture geometries in the wall.